1. Field of the Invention
The present invention relates in general to turbochargers for automotive engines and more particularly to a turbocharger rotor assembly adapted for support by ball bearings.
2. Description of the Prior Art
A turbocharger rotor assembly having a rotor shaft adapted for support by two ball bearings on the turbine side and compressor side is well known in the art and herein referred to as a ball bearing type turbocharger rotor assembly.
The rotor assembly includes, in addition to the rotor shaft, a turbine wheel, an inner ring of a turbine side ball bearing and a tubular spacer which are installed on the rotor shaft. The spacer is provided for locating an inner ring of a compressor side ball bearing relative to the inner ring of the turbine side bearing upon installation of the compressor side bearing on the rotor shaft.
Heretofore, measurement and correction of the unbalance of a turbocharger rotor has been performed in the state of the above described rotor assembly wherein the inner ring of the bearing and spacer are installed on the rotor shaft. In measurement of the unbalance, the rotor assembly is rotatably supported at the ball race of the inner ring.
A problem of the rotor assembly is that there is a difficulty in knownin a precise amount of its unbalance since an error in measurement of the unbalance tends to become large.